In this study of the mechanism whereby 1,2-dimethylhydrazine causes colon cancer, several specific programs will be pursued: 1. Methods of development will be continued for the separation and identification of metabolites of dimethylhydrazine. This includes resolution of the difficult problem of the reliable synthesis and acquisition of the carbon-14 labeled chemical. 2. Additional data will be gathered on the in vivo metabolism of the agent in several species with reported distinct carcinogenic response to dimethylhydrazine. This includes a comparison of the metabolism in various rodent strains which do and do not show cancer in the small intestine and large bowel, and guinea pigs which with azoxymethane develop liver disease but not colon cancer. 3. In vitro studies will be conducted on the capability of various segments of the intestinal tract to metabolize dimethylhydrazine. Carcinogenicity studies will be performed with short regimens of dimethylhydrazine administration and the modification of the response with enzyme inducers and other environmental agents will be determined.